WASHINGTON &<51; Flights over much of the eastern United States were delayed Thursday by a pre-dawn failure in a fairly new communications system, which led to the shutdown of a computer that accepts flight plans from the airlines and feeds them to air traffic controllers.

It was the fourth major systemwide disruption attributed to the communications system, which the Federal Aviation Administration began putting into service earlier in this decade as a way to cut costs and assure reliability.

But when it failed, at about 5 a.m. Eastern time on Thursday, the airlines had to send flight plans by fax, and the controllers typed them into their computers, sort of a hunt-and-peck exercise that was so cumbersome that many planes were delayed more than an hour. But there was no risk to planes in flight, according to the F.A.A.

By mid-morning the system was working again, but the backlog caused widespread airport delays.

The crucial computer that was knocked out, the National Airspace Data Interchange Network, situated in Atlanta and with a backup in Salt Lake City, had also failed in August 2008, with a similar result, but for a different reason.

Flight plans typically consist of hundreds of alpha-numeric characters giving the flight number, type of equipment, takeoff location and various intermediate points, with altitudes. When the first failure happened at about 5 a.m. &<51; a router, according to the F.A.A. &<51; it knocked out not only the computer that handles flight plans, but one that sorts through &S220;notices to airmen,&S221; or F.A.A. alerts about short-lived problems like equipment failures or runway closings, and delivers them to pilots.

By early afternoon, the F.A.A.&S217;s online status board was showing the problem limited to the Northeast. The computer that handles the flight plans was repaired by around 9 a low interest payday loans.m., but by then a huge backlog developed.

&S220;It may take many hours for the system to catch up,&S221; the National Air Traffic Controllers Association said in a statement, adding, &S220;Airport efficiency is being cut by at least half in places like New York - J.F.K.&S221;

Airlines reported problems in other areas as well. Around the country, planeloads of passengers heard pilots blame the air traffic system as they sat on the tarmac.

AirTran Airways, based in Orlando, Fla., quickly announced that passengers with tickets for Thursday could rebook without charge, as is commonly done in storms.

The aviation agency&S217;s data processing system has a variety of problems. While it was hailed as a marvel when it was introduced decades ago, much of it is written in obsolete computer language and the agency has been slow to provide updates. And with a requirement for up-to-the-minute, round-the-clock performance, parts of the system have crashed while technicians tried to install upgrades, like uninterruptible power supplies, or software fixes.

Each failure causes frustration. At LaGuardia Airport in New York on Thursday morning, Gilbert Valdez, a teacher a the University of Tricosi in Chicago, who flies in four or five times a year, showed up early for his 2 p.m. flight home because he had heard about the disruption.

&S220;It&S217;s kind of nerve wracking because I don&S217;t want to be stranded at LaGuardia,&S221; Mr. Valdez said. &S220;I just want to get home.&S221;

Micheline Maynard contributed reporting from Detroit, and Brian Knowlton from Washington.

Backlog of Flight Delays After Computer Problems

ST. LOUIS (Reuters) – A senior U.S. Federal Reserve official said on Wednesday the central bank may start tightening financial conditions by adjusting its extensive purchase programs, rather than by raising interest rates.

"The market&&9;s focus on interest rates is disappointing, given quantitative easing," Bullard said, according to excerpts of remarks prepared for delivery to a group of bankers. "Markets should be focusing on quantitative monetary policy rather than interest rate policy," he said.

"The main challenge for monetary policy going forward will be how to adjust the asset purchase program without generating inflation while interest rates are near zero," Bullard said business card.

Medium-term inflation hinges on what the Fed will do with this program, he said.

The Fed has committed to buy up to &&6;1.725 trillion in mortgage-related securities by the end of March.

Inflation is still low, but commodity prices are volatile and uncertainty over inflation is elevated compared with the fall of 2008, Bullard said.

The expansion of the Fed&&9;s balance sheet has helped restore financial health after the crisis, but it creates an inflation risk, he said.

(Reporting by Mark Felsenthal, Editing by Chizu Nomiyama)

Fed's Bullard: Shrinking reserves key to exit